Liquid nonionic surfactant combination having improved low-temperaturestability

ABSTRACT

Liquid nonionic surfactant combination having improved low temperature stability which comprises: 
     (a) from about 20% to about 50% by weight of an alcohol ethoxylate derived from primary linear C 12-15  alcohols having an average degree of ethoxylation equal to from about 2 to about 7; 
     (b) from about 20% to about 50% by weight of an alcohol alkoxylate derived from primary saturated alcohols containing 12 to 15 carbon atoms in which the alcohol radical can be linear, methyl-branched in the 2-position, or a mixture of said linear and said methyl-branched radicals, having an average degree of ethoxylation equal to from about 3 to about 7 and an average degree of propoxylation equal to from about 2 to about 8; 
     (c) from about 5% to about 50% by weight of an alcohol ethoxylate derived from oxoalcohol mixtures of primary, linear, and 2-methyl-branched C 12-15  alcohols having an average degree of ethoxylation equal to from about 2 to about 8.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a liquid nonionic surfactant combination whichis pourable at low temperatures and which is stable in storage over awide temperature range from -10° to +40° C.

2. Statement of Related Art

Surfactant combinations of the type in question are used in particularas liquid concentrates together with so-called washing alkalis and areparticularly suitable for the washing of oil-stained textiles andworking apparel in laundries. Liquid concentrates which can beautomatically metered are particularly valuable for an application suchas this. In addition to the properties mentioned, liquid concentratesare virtually unaffected in their viscosity behavior by variations intemperature.

Known pourable concentrates used for purposes of the type in questiontypically contain solvents, more particularly low molecular weightalcohols, to guarantee the necessary low-temperature stability. In manycases, low molecular weight polyglycols or polypropylene glycol areadded to them to improve not only their low-temperature stability, butalso their viscosity behavior in the required manner. However, neitheraddition makes any contribution to the washing effect.

Accordingly, the problem addressed by the present invention was toprovide a corresponding liquid concentrate which, despite no additionsof solvent, would be stable over a relatively wide temperature range andwhich would be easy to meter at various temperatures without significantchanges in viscosity. At the same time, the washing and cleaningproperties, particularly with respect to oil- and grease-containingsoil, would not be reduced by comparison with known leading products,but instead would be fully maintained or even increased. This problemhas been solved by the invention described in detail hereinafter,

DESCRIPTION OF THE INVENTION

The present invention relates to a liquid nonionic surfactantcombination having improved low-temperature stability which contains

(a) 20 to 50% by weight of an alcohol ethoxylate derived from primarylinear C₁₂₋₅ alcohols containing on average 2 to 7 ethylene oxide groups(EO),

(b) 20 to 50% by weight of an alcohol alkoxylate derived from primaryC₁₂₋₁₅ alcohols containing an average of 3 to 7 ethylene oxide groups(EO) and 2 to 8 propylene oxide groups (PO),

(c) 5 to 50% by weight of an alcohol ethoxylate derived from mixtures ofprimary, linear and 2-methyl-branched C₁₂₋₁₅ alcohols (oxoalcohols)containing an average of 2 to 8 ethylene oxide groups.

All the degrees of alkoxylation mentioned are statistical mean valueswhich may be a whole or broken number for a special product. Preferredalcohol alkoxylates (a) and (b) are the narrow-range ethoxylates (nre).Alcohol alkoxylates (b), in which the propylene oxide distribution alsocorresponds to a narrow-range homolog distribution, are particularlypreferred.

The nonionic component (a) preferably consists of an alcohol ethoxylatederived from primary, saturated and linear alcohols containing 12 to 14carbon atoms, for example of the type present in alcohol mixturessynthesized by the Ziegler method or obtained from native fatty acids byreduction. The preferred alcohol mixtures of native origin may containsmall amounts of C₁₀ or C₁₆ alcohols, although the percentage content ofC₁₆ alcohols should be less than 10% by weight and, more particularly,less than 5% by weight while the percentage content of C₁₀ alcoholshould be less than 15% by weight and, more particularly, less than 10%by weight. The degree of ethoxylation (EO) of the nonionic component (a)is preferably 2 to 5. The surfactant combination preferably contains 20to 45% by weight and, more preferably, 25 to 40% by weight of component(a).

The nonionic component (b) is derived from primary saturated alcoholscontaining 12 to 15 carbon atoms in which the alcohol radical may belinear or methyl-branched in the 2-position or may contain mixed linearand methyl-branched radicals such as are typically present in oxoalcoholradicals. However, linear radicals of C₁₂₋₁₄ alcohols of native origin,which may optionally contain corresponding amounts of C₁₀ and C₁₆alcohol radicals, are preferred. Component (b) contains both ethyleneoxide groups (EO) and propylene groups groups (PO). These groups may bestatistically distributed, although it is preferred to use compounds inwhich the alcohol radical is first completely ethoxylated and thenpropoxylated, as reproduced by the schematic formula R--(EO)_(x)--(PO)_(y). In this formula, R represents the alcohol radical, xrepresents the number of (EO) groups and y represents the number of (PO)groups. The number of EO groups is preferably from 4 to 6 while thenumber of PO groups is preferably from 2 to 5 and, more preferably, 2.5,3 and 4. If the number of EO groups is larger than 5, a relatively largenumber of PO groups, for example 5 to 6, is also recommended. Analkoxylate containing (on average) 4 to 6 EO groups and 2 to 3 PO groupshas proved to be particularly suitable in ecological terms. Thepercentage content of component (b) in the concentrate is preferablyfrom 20 to 45% by weight and, more particularly, from 25 to 40% byweight.

Component (c) is derived from oxoalcohols which are known to be amixture of linear and 2-methyl-branched alcohols, in which thepercentage content of linear alcohols generally dominates. The alcoholradicals contain 12 to 15 and preferably 13 to 14 carbon atoms.Technical mixtures may additionally contain small components containing11 or 15 carbon atoms, although their percentage content shouldpreferably be less than 10% by weight, based on the technical mixture.The degree of ethoxylation of component (c) is preferably from 2 to 5and, more preferably, from 2.5 to 4. The percentage content of component(c) in the concentrate is preferably from 10 to 45% by weight and, morepreferably, from 15 to 40% by weight.

The concentrates may be anhydrous or may contain up to 20% by weight andpreferably 5 to 15% by weight water. The water content is of minorimportance so far as low-temperature stability and metering propertiesare concerned. However, since the nonionic surfactants (a), (b) and (c)are technical products which are obtained and marketed in variousqualities and purities, the concentrates can cloud where certaintechnical product batches are used or can even form gel-likeprecipitates. Such clouding and precipitation is reliably avoided byaddition of water, additions of 5 to 10% by weight generally beingsufficient for this purpose.

The concentrates may contain other additives providing they are solubleand do not affect the favorable properties of the concentrates. Theadditives in question include, in particular, dyes and fragrances withwhich the color and odor of the mixtures is masked. Although solventsmay basically be added, they are neither necessary nor appropriate forthe reasons explained above.

The concentrates behave in the manner of newtonian liquids, in otherwords their viscosity is independent of the shear forces acting on them.Accordingly, they are easy to transport and to meter, their viscosityundergoing comparatively little change as a function of temperature.Even after storage for several months in a conditioned atmosphere withtemperatures repeatedly changing between -10° C. and +40° C., they arestable in storage, i.e. have no tendency towards separation. Theconcentrates are liquid in consistency to at least 0° C. Between -10° C.and 0° C., they may be present in liquid or solid form. Even theconcentrates present in solid form at temperatures of this order giveclear and homogeneous liquids on thawing. These properties make themparticularly suitable for fully automatic metering in institutionallaundries.

Although the concentrates may be used for the preparation of washliquors without any further additives, they are preferably used incombination with typical builders, so-called washing alkalis,co-builders and sequestering agents and other typical detergentadditives.

Suitable builders are, for example, finely crystalline zeolites of theNaA type and phosphates, more particularly pentasodium triphosphate.Suitable washing alkalis are soda and sodium silicates, moreparticularly metasilicate and silicates having the composition Na₂ O:SiO₂ =1:1.5 to 1:3.3. Suitable co-builders are polymericpolycarboxylates, more particularly homopolymers of acrylic acid andcopolymers of acrylic acid with maleic acid. Suitable complexing agentsor sequestering agents are aminopolycarboxylates, such as sodiumnitrilotriacetate, ethylenediamine tetraacetate and higher homologsthereof, phosphonates, such as 1-hydroxyethane-1,1-diphosphonate,aminotri(methylenephosphonate), ethylenediaminetetra-(methylenephosphonate) and higher homologs thereof, such asdiethylenetriamine penta-(methylenephosphonate).

Other suitable additives are redeposition inhibitors, for examplecellulose ethers, such as carboxymethyl cellulose, methyl cellulose,hydroxyalkyl celluloses containing C₂₋₄ hydroxyalkyl radicals and mixedethers, such as alkyl hydroxyalkyl cellulose. Other suitable additivesare optical brighteners, enzymes, bleaches from the class of percompounds, which are normally used together with activators, and activechlorine compounds, foam inhibitors and also dyes and fragrances.

In cases where the concentrates according to the invention are added asdetergency boosters or to improve the oil- and grease-removing power oftypical detergents, the detergents may also contain typical anionic andnonionic surfactants, including linear alkyl benzenesulfonates, such asC₉₋₁₃ alkyl benzene sulfonate, alkane sulfonates, α-sulfofatty acids andfatty alcohol sulfates. In addition, these detergents may containtypical nonionic surfactants, more particularly ethoxylates of C₁₂₋₁₆fatty alcohols and C₁₂₋₁₆ oxoalcohols. Through the use of the surfactantcombinations according to the invention, there are no limitations inregard to the choice and quantity of these and the above-mentionedingredients because they are highly compatible with the substances inquestion.

The detergent ingredients and additives mentioned are normally storedseparately from the surfactant combination according to the inventionand are added to the wash liquor as and when required, generally in theform of preformed mixtures. For institutional application, soft water isgenerally used.

The nonionic surfactant combination according to the invention inconjunction with the detergent ingredients mentioned above isparticularly suitable for washing heavily soiled working apparel and isdistinguished by high washing power with respect to stains containingmineral oil.

EXAMPLES Example 1

The linear C₁₂₋₁₄, alcohol alkoxylates (components a and b) used toproduce the surfactant combination had the following C chaindistribution: C₁₀ 0.5% by weight, C₁₂ 72.5% by weight, C₁₄ 26.0% byweight, C₁₆ 1.0% by weight. The concentrate had the followingcomposition:

(a) 30% by weight C₁₂₋₁₄ alcohol+3 EO (nre)

(b) 30% by weight C₁₂₋₁₄ alcohol+5 EO+4 PO (nre)

(c) 30% by weight C₁₃ oxoalcohol+3 EO

(d) 10% by weight water.

The clear concentrate was exposed to a temperature varying from -10° C.to +40° C. in a 12-hour cycle over a period of 5 months in a conditionedatmosphere and showed no signs of separation. Slight clouding whichbegan at -5° C. disappeared again at 0° C., Another sample stored forseveral months at -5° C. showed identical behavior.

Viscosity measurements carried out with a Carrimed rotational rheometerproduced the following results:

    ______________________________________                                                °C.                                                                         mPa · s                                                 ______________________________________                                                 0   252                                                                       5   162                                                                      10   115                                                                      15    84                                                                      20    62                                                              ______________________________________                                    

The viscosity was independent of the shear rate (no thixotropy) over themeasuring range (5 s⁻¹ to 100 s⁻¹).

The washing tests were carried out as follows: "Frista" automaticwashing machine, capacity 7.5 kg, quantity used 5 kg normally soiledtextiles (ballast washing) plus artificially soiled test swatches Waterhardness 0° Gh.

Ratio of washing to wash liquor 1:7.5

1st Wash cycle 15 mins. at 80° C. with 75 ml surfactant combination and175 g washing powder

2nd Wash cycle 15 mins. at 70° C. with 175 g washing powder.

After the first wash cycle, the wash liquor was drained off and thewashing was rinsed once with water at 70° C. After the 2nd wash cycle,the washing was rinsed 5 times.

The washing powder added had the following composition (in % by weight):

    ______________________________________                                        C.sub.9-13 alkyl benzene sulfonate                                                                1.6                                                       C.sub.12-16 fatty alcohol + 7 EO                                                                  3.0                                                       Na.sub.5 P.sub.3 O.sub.10                                                                         20.0                                                      Soda                25.0                                                      Sodium metasilicate 45.0                                                      Cellulose ether     1.5                                                       Hydroxyethane diphosphonate                                                                       0.4                                                       Optical brightener  0.1                                                       Water               Balance                                                   ______________________________________                                    

The following artificially soiled test swatches were tested:

I) carbon black, vegetable fat and mineral oil on crease-resistantcotton

II) carbon black, vegetable fat and mineral oil on a blend of polyesterand crease-resistant cotton

III) carbon black and mineral oil on crease-resistant cotton

IV) dust and sebum on cotton.

Two liquid concentrates A and B, which are commercially availablesolvent (alcohol, glycols)-containing products for the same field ofapplication, were used for comparison. They are both among the leadingproducts in the field in question. The results are set out in thefollowing Table. The figures represent photometrically determinedremission values.

    ______________________________________                                               Remission (in %)                                                       Soil     Example 1       A      B                                             ______________________________________                                        I        54.3            52.7   53.6                                          II       45.7            44.5   45.2                                          III      69.6            69.0   69.5                                          IV       65.9            64.5   64.5                                          ______________________________________                                    

Washing tests with a phosphate-free zeolite-containing detergentproduced comparable results.

Example 2

A surfactant combination had the following composition (in % by weight):

    ______________________________________                                        C.sub.12-14 alcohol + 3 EO (nre)                                                                     40                                                     C.sub.12-14 alcohol + 5 EO + 4 PO (nre)                                                              40                                                     C.sub.13 oxoalcohol + 3 EO                                                                           10                                                     Water                  10                                                     ______________________________________                                    

The combination was stable at temperatures varying from -10° C. to +40°C. Clouding which began at 0° C. disappeared again at +3° C. Thecombination had the following viscosities at the temperatures shownirrespective of the shear rate:

    ______________________________________                                                °C.                                                                         mPa · s                                                 ______________________________________                                                 5   170                                                                      10   116                                                                      15    87                                                                      20    63                                                              ______________________________________                                    

It was equivalent and, in individual cases (samples I and II), superiorin its washing performance to the combination of Example 1.

Example 3

A surfactant combination had the following composition (in % by weight):

    ______________________________________                                        C.sub.12-14 alcohol + 3 EO (nre) 25                                           C.sub.12-14 alcohol + 5 EO + 2.5 PO                                                                (narrow-range                                                                 homolog distri-                                                               bution for EO                                                                 and PO)     20                                           C.sub.13 oxoalcohol + 8 EO       25                                           C.sub.13 oxoalcohol + 3 EO       10                                           Water                            10                                           ______________________________________                                    

The combination was stable at temperatures varying from -10° C. to +40°C., i.e. a clear homogeneous liquid with no tendency to separate waspresent, even after repeated changes in temperature. The combination hadthe following viscosities at the temperatures shown irrespective of theshear rate:

    ______________________________________                                                °C.                                                                         mpa · s                                                 ______________________________________                                                 0   329                                                                       5   222                                                                      10   156                                                                      15   113                                                                      20    85                                                              ______________________________________                                    

It was equivalent in its washing performance to the combination ofExample 1.

What is claimed is:
 1. A liquid nonionic surfactant combination havingimproved low temperature stability which consists essentially of:(a)from about 20% to about 50% by weight of an alcohol ethoxylate derivedfrom primary linear C₁₂₋₁₅ alcohols having an average degree ofethoxylation equal to from about 2 to 7; (b) from about 20% to about 50%by weight of an alcohol alkoxylate derived from primary saturatedalcohols containing 12 to 15 carbon atoms in which the alcohol radicalcan be linear, methyl-branched in the 2-position, or a mixture of saidlinear and said methyl-branched radicals, having an average degree ofethoxylation equal to from about 3 to about 7 and an average degree ofpropoxylation equal to from about 2 to about 8; and (c) from about 5% toabout 50% by weight of an alcohol ethoxylate derived from oxoalcoholmixtures of primary, linear, and 2-methyl-branched C₁₂₋₁₅ alcoholshaving an average degree of ethoxylation equal to from about 2 to about8 the balance comprising not more than 20% by weight water.
 2. Thecomposition of claim 1 wherein said component (a) is derived fromprimary linear C₁₂₋₁₄ alcohols having an average degree of ethoxylationequal to from about 2 to about
 5. 3. The composition of claim 1 whereinthe amount of component (a) is from about 20% to about 45% by weight. 4.The composition of claim 3 wherein the amount of component (a) is fromabout 25% to about 40% by weight.
 5. The composition of claim 1 whereinsaid component (b) is derived from primary linear C₁₂₋₁₄ alcohols of theformula

    R--(EO).sub.x --(PO).sub.y --OH

wherein R is a linear C₁₂₋₁₄ alcohol radical, EO is an ethylene oxidegroup, PO is a propylene oxide group, x is a number from about 3 toabout 7 and y is a number from about 2 to about
 8. 6. The composition ofclaim 5 wherein x is a number from about 4 to about 6 and y is a numberfrom about 2 to about
 5. 7. The composition of claim 11 wherein theamount of component (b) is from about 20% to about 45% by weight.
 8. Thecomposition of claim 7 wherein the amount of component (b) is from about25% to about 40% by weight.
 9. The composition of claim 1 wherein saidcomponent (c) is derived from a mixture of primary linear and 2-methylbranched C₁₃₋₁₄ alcohols having an average degree of ethoxylation equalto from about 2.5 to about
 4. 10. The composition of claim 1 wherein theamount of component (c) is from about 10% to about 45% by weight. 11.The composition of claim 1 further comprising up to about 20% by weightof water.
 12. The composition of claim 11 wherein the amount of water isfrom about 5% to about 15% by weight.
 13. A process for cleaning asoiled fabric selected from the group consisting of cotton, and a blendof polyester and crease-resistant cotton which comprises contacting saidfabric with a composition of claim 1 in an aqueous washing liquor. 14.The composition of claim 6 wherein y is a number of from about 2 toabout
 3. 15. The composition of claim 1 wherein in component (c) thedegree of ethoxylation, is from about 2 to about
 5. 16. The compositionof claim 25 wherein said degree of ethoxylation is from about 2.5 toabout
 4. 17. The composition of claim 1 wherein the amount of component(c) is from about 15 to about 40% by weight.
 18. The composition ofclaim 1 wherein the amount of component (a) is from about 20% to about45% by weight, and component (a) is derived from primary linear C₁₂₋₁₄alcohols having an average degree of ethoxylation equal to from about 2to about 5; the amount of component (b) is from about 20% to about 45%by weight; and the amount of component (c) is from about 10% to about45% by weight, and component (c) is derived from a mixture of primarylinear and 2-methyl branched C₁₂₋₁₄ alcohols having an average degreeethoxylation equal to from about 2 to about
 5. 19. The composition ofclaim 18 wherein component (b) is derived from primary linear C₁₂₋₁₄alcohols of the formula

    R--(EO).sub.x --(PC).sub.y --OH

wherein R is a linear C₁₂₋₁₄ alcohol radical, EO is an ethylene oxidegroup, PO is a propylene oxide group, x is a number from about 3 toabout 7 and y is a number from about 2 to about
 8. 20. The compositionof claim 19 wherein the amount of component (a) is from about 25% toabout 40% by weight; the amount of component (b) is from about 25% toabout 40% by weight; and the amount of component (c) is from about 15 toabout 40% by weight.